Re: [Qemu-devel] [PATCH 1/2] ide: ide-cd without drive property for empty drive

[Eric Blake <eblake@redhat.com>]

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On 08/01/2016 01:47 PM, Kevin Wolf wrote:
> Am 14.07.2016 um 21:48 hat Eric Blake geschrieben:
>> On 07/14/2016 07:49 AM, Kevin Wolf wrote:
>>> This allows to create an empty ide-cd device without manually creating a
>>> BlockBackend.
>>>
>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>> ---
>>>  hw/ide/qdev.c | 20 +++++++++++++++-----
>>>  1 file changed, 15 insertions(+), 5 deletions(-)
>>
>>> @@ -158,6 +154,16 @@ static int ide_dev_initfn(IDEDevice *dev, IDEDriveKind kind)
>>>      IDEState *s = bus->ifs + dev->unit;
>>>      Error *err = NULL;
>>>  
>>> +    if (!dev->conf.blk) {
>>> +        if (kind != IDE_CD) {
>>> +            error_report("No drive specified");
>>> +            return -1;
>>> +        } else {
>>> +            /* Anonymous BlockBackend for an empty drive */
>>> +            dev->conf.blk = blk_new();
>>
>> So we either fail or dev->conf.blk is set...
>>
>>> +        }
>>> +    }
>>> +
>>>      if (dev->conf.discard_granularity == -1) {
>>>          dev->conf.discard_granularity = 512;
>>>      } else if (dev->conf.discard_granularity &&
>>> @@ -257,7 +263,11 @@ static int ide_cd_initfn(IDEDevice *dev)
>>>  
>>>  static int ide_drive_initfn(IDEDevice *dev)
>>>  {
>>> -    DriveInfo *dinfo = blk_legacy_dinfo(dev->conf.blk);
>>> +    DriveInfo *dinfo = NULL;
>>> +
>>> +    if (dev->conf.blk) {
>>> +        dinfo = blk_legacy_dinfo(dev->conf.blk);
>>> +    }
>>>  
>>>      return ide_dev_initfn(dev, dinfo && dinfo->media_cd ? IDE_CD : IDE_HD);
>>
>> ...yet, this claims dev->conf.blk can be NULL.  What am I missing?
> 
> That ide_drive_initfn() is the outer function and runs first, before we
> handle the case in ide_dev_initfn()?

Ah, I think I glazed over the difference between 'dev' and 'drive', and
was thinking 'both of these are initfn, what's different?'.  I think you
are okay, after all.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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